Safety device for water systems



Aug. 13, 1940. F; M. DAWSON SAFETY DEVICE FOP. WATER SYSTEMS Filed Aug. 19, 1938 Fig. 4 m/ 40 Q Fig.5 I (.40 INVENTOR. .FRHNC/6 DF/WSON m =1, M 7m 6? ATTORNEYS.

' having an opening in its inner wall.

Patented Aug. 13, 1940 UNITED STATES PATENT OFFICE 6 Claims.

. This invention relates to safety devices, commonly known as vacuum breakers, for use with water systems and which prevent the siphoning of dirty water back into the water supply in case there is a drop in pressure. In the arrangement illustrated, it is embodied in the inlet water system of a washing machine.

It sometimes happens that, due to the opening of other outlets or for other reasons, the pressure at an outlet of a water supply system will drop temporarily below atmospheric presure. It is an important object of the present invention to prevent this drop in-pressure from'causing' siphoning of dirty water back into the water supply, without in any way interfering with the normal delivery of water when ordinary pressures build up again.

Preferably this is accomplished effectively and at low cost by interposing, in the conduit connections from the source of water to a washing machine or other apparatus which uses the water, a conduit section formed in an are or loop At normal pressures, the water is swept past the opening by centrifugal force; in case of a drop in pressure, however, air is sucked in at the opening and it is impossible for any reverse siphoning action to start.

When used with a washing machine or the like, the curved section or loop is conveniently arranged vertically, above the water level in the machine, in the inlet conduit connections.

I prefer to flatten the' arcuate conduit section,

so that the conduit thickness radially, at the bend, is less than the normal conduit diameter. The opening in the inner wall should be large relatively to the conduit cross-sectional area, and in fact should, to give maximum protection be some three times as large. It is an important advantage of my invention that such a large opening can be used without danger of spilling any substantial amount of water in normal operation.

The above and other objects and features of' conduit respectively on the lines 3-3, 4-4, and 5-5 of Figure 2.

The automatic washing machine shown in Figure 1 is of the construction fully described in application No. 129,429, flied March 6, 1937, by Rex 5 Earl Bassett, Jr. and John W. Chamberlin, and in application No. 129,412, filed March 6, 1937, by Adiel Y. Dodge.

It includes a base comprising a pair of saddles ID, in which is secured by straps 12 or the like 10 a cylindrical tub I4 arranged with its axis horizontal, and which has in one end an opening closed by a suitable door and through which the clothes are inserted and removed. Within the tub I4 is a perforated cylindrical" open-ended 15 clothes drum l6, formed with bafiles l8, which' is rotated about a horizontal axis by a belt 20 driven by a motor-transmission unit 22. This unit drives the drum at a relatively low speed for washing and at a much higher speed for 20 drying by centrifugal extraction.

The hot and cold water used in the machine is delivered to the tub M, from suitable sources of supply, under the control of a solenoid-operated valve unit 24, through an inlet conduit 26 dis- 25 charging into the tub l4 through a nozzle 28, The maximum water level in the tub is determined bya float in a float chamber 30 'communicating with the bottom ofthe tub, the float being connected to operate a float switch 32 30 arranged in series in one of the lines leading to the valve unit 24, so that the inlet valves close automatically whenever the water in the tub reaches a predetermined level. Y

The tub I4 is also provided with a drain mech- 35 anism 34 having a solenoid control.

The solenoids of the valve unit 24, the solenoid of the drain unit 34, and the speed-control means of the motor-transmission unit 22, are all controlled automatically by a multiple motor-driven 0 switch 3|, as described in the above-identified application No. 129,429, to cause the machine to operate automatically in a predetermined cycle to wash and rinse and dry the clothes in the drum l6.

Whether or not embodied in the particular machine described above, the present invention has to do with providing a safety device protecting against siphoning of dirty water from the machine back into the supply main. Occasionally, in most water systems, because of the opening of faucets further'back along the supply main or for some other reason the pressure at an outlet (such as the intake of this machine) drops sharply, and it sometimes happens that it actually drops below atmospheric pressure.

In such an event, if there is no special means to prevent it, and if the nozzle 28 chances to be in or near the surface of the suds in the machine, the dirty water may siphon back into the supply main. This may happen even if the valve unit 24 is closed, if the suction is strong enough to unseat the valve.

The safety device embodying my invention which is illustrated in the drawing is in the form of a conduit section 40, interposed in the intake conduit means 26 ahead of the nozzle 28 above the highest possible water level in the machine, and shown supported adjacent the top of the tub M. This conduit section 40 is in arcuate form, 1. e. it is a downwardly facing loop, the opposite vertical legs beingconnected respectively to the conduit 26 from the valve unit 24 and to the nozzle 28.

The upper or bent portion of this loop is flattened, as will be apparent from a comparison of Figures 3, 4, and 5, and is formed on its lower or inner face with a relatively large opening 42. The sides of the tube may be bent down parallel to each other opposite this opening, as shown in Figure 3. The opening is preferably quite large, e. g. three times or more the cross-sectional area of the conduit, to insure that any siphon action will be eflectively broken.

The parts of the bottom wall at the ends of the opening 42 may be formed as tongues 44 and 46 bent upwardly into the conduit to form continuations of the bottom walls of the flattened portions at the ends of the opening 42, one of which is illustrated in Figure 4. The tongue 44, on the inlet side of opening 42, is preferably bent somewhat further into the conduit than tongue 46, and the conduit may be flattened somewhat more on the inlet side of the opening than on the nozzle side.

I prefer, in an installation such as a washing machine of the described type, where the leakage of even a small amount of water is undesirable,'to provide an overflow chamber, shown as a trough 48, below the opening. The trough 48 is shown with the legs of the conduit section 40 passing throughits bottom and sealed thereto, for example by solder. It may be provided with a drain conduit 50 emptying into the tub l4.

' In operation, the water normally rises in con-' duit 25 under considerable pressure, and sweeps around the loop 40 under sufflcient centrifugal force so that it passes the opening 42' without spilling out. The opening 42 insures that the pressure at this point will not be greater than atmospheric pressure;' in fact the device may be so formed that there isan injector action at this point suflicient to give a slight subatmospheric pressure, since there is no harm in sucking a small amount of air into the tub.

If the pressure at and below the valve unit 24 should drop below atmospheric pressure, the result will merely be to suck air in at the opening 42, as it is impossible (with the large opening 42 shown) to exert suflicient auction on the nozzle 28 to raise any dirty water from the lev'el'of the nozzle to the level of the device 40, even if nozzle 28 chances to be below the suds level.

By forming the device 40 to have a substantial injector action, it is even possible to use it as a mixing device, for various kinds of apparatus, to suck one fluid in through the opening 42 and mix it with another fluid passing through the conduit.

I While one illustrative embodiment has been described in detail, it is not my intention to limit the scope of the invention to that particular embodiment, or otherwise than by the terms of the appended claims.

I claim:

1. A device comprising a conduit section adapted to be connected to a source of liquid under pressure and bent in an arc formed to throw a liquid passing through the conduit centrifugally against its outer wall and provided with an opening in its inner wall to admit air into the conduit when the pressure drops at said source, in combination with an overflow chamber arranged below said opening.

2. A device comprising a conduit section bent in an are formed to throw a liquid passing through the conduit centrifugally against its duter wall and provided with an opening in its inner wall, said section being flattened at said arc so that it is considerably reduced in thickness radially of the are relatively to the parts of said section before and after said are to minimize spillage from said opening as the.

liquid passes across the opening.

3..A device comprising a conduit section bent in an are formed to throw a liquid passing through the conduit centrifugally against its outer wall and provided with an opening in its inner wall, said section beingIflattened-at said are so that it is considerably reduced'in thickness radially of the are relatively to the parts of said section before and after said are to minimize spillage from said openingas the liquid passes across the opening, said opening being larger in area thanthe cross-sectional area of the conduit section.

4. A device comprising a conduit section formed in a loop and fiattened' transversely at the curved portion of the loop and having an opening in the inner wall of the loop, said section being flattened more at one end of said opening than at the other to minimize spillage from said opening as liquid passes across the opening.

5. A device comprising a conduit section bent in an arc to throw liquid passing through the conduit centrifugally against its outer wall and provided with an opening in its inner wall which is relatively large as compared with the conduit section, said conduit section being flattened at said arc so that its wall portion facing the center of curvature is flat and said opening being formed solely in said flat wall portion.

- 6. A device comprising a conduit section bent in an arc to throw liquid passing through the conduit centrifugally against its outer wall and provided with an opening in its inner wall which is relatively large as compared with the conduit section, said conduit section being flattened at said are to a substantially rectangular section having its sides adjacent said opening extending radially inward of the conduit to prevent the flow of liquid from the opening laterally of the conduit.

FRANCIS M. DAWSON. 

